1. Field of the Invention
The present invention relates to a disposable diaper. More particularly, the present invention relates to a disposable diaper having a satisfactory expansion and contraction property and a fiber-fabric-like skin feeling, where at least the side liner portions of which diaper are formed from a specific stretchable, moisture-permeable composite sheet.
The disposable diaper of the present invention is useful for babies and incontinent persons.
2. Description of the Related Art
Japanese Unexamined Patent Publication (Kokai) No. 3-80,859 discloses a disposable undershirt in which a sheet prepared by segmentally or separately adhering a stretchable film to an inside surface of a stretchable nonwoven fabric is employed as a back sheet. Also, Japanese Unexamined Patent Publication (Kokai) No. 3-162,854 discloses a disposable garment in which a stretchable film is segmentally or separately attached to an inside surface of a stretchable nonwoven fabric to form a sheet, and a plurality of air-permeable holes are formed on both side edge portions of the stretchable film on the sheet.
The disposable diaper includes an underpants type disposable diaper in which the front waist section and the back waist section of the diaper are adhered and fixed to each other at side edge portions thereof so as to form a waist opening and a pair of crotch openings. The underpants type disposable diaper can be put on and taken off by the wearer himself and thus is useful for diaper-wearing children and incontinent adults. Recently, the demand for underpants type disposable diapers has been increasing.
For the underpants type disposable diaper, it is required that the crotch opening portions, waist opening portions and waist side portions are appropriately fit to the wearer. Therefore, the above-mentioned portions are formed from a stretchable elastic material.
Japanese Unexamined Patent Publication No. 2-4364 discloses an underpants type disposable diaper having a liquid-absorbent pad member formed from a liquid-permeable top sheet, a liquid non-permeable back sheet and a liquid absorbent pad arranged between the top and back sheet, and a pair of stretchable side panels attached to side edge portions of the liquid absorbent pad member.
This type of diaper has a satisfactory leak-preventing property at the waist and crotch opening portions. However, this diaper is disadvantageous in that a.sub.0 the waist portions exhibits an unsatisfactory fit to the wearer; b.sub.0 when the stretchable side panels are attached to the liquid absorbent pad member, since the middle portions of the side panels are attached in a stretched condition to the crotch portions of the liquid absorbent pad member, and the remaining portions of the side panel are in a non-stretched condition, it is difficult to fix the stretchable side panels in the stretched condition at predetermined intervals in a direction in which the diaper-production line moves; c.sub.0 the stretchable side panels are not strong enough to fit the diaper to the wearer; and d.sub.0 since the crotch opening portions have no gathers, the diaper is unsatisfactory in preventing the liquid from leaking through the crotch openings.
Also, another underpants type disposable diaper comprising an absorbent pad member formed from a top sheet, a back sheet and an absorbent pad arranged between the above-mentioned sheets, and an outermost sheet member for fixing the absorbent pad member thereon and holding the diaper on the wearer by bringing the outermost sheet member into contact with the wearer, is disclosed in Unexamined PCT Publication (Kokai) No. 1-503,473 in Japan, Japanese Unexamined Patent Publication (Kokai) No. 4-161,152, Japanese Unexamined Patent Publication (Kokai) No. 5-76,565 or Japanese Unexamined Patent Publication (Kokai) No. 6-63,074.
The disposable diaper disclosed in Japanese Unexamined Patent Publication (Kokai) No. 3-80,859 and Japanese Unexamined Patent Publication (Kokai) No. 3-162,854, in which a diaper consists of a sheet prepared by segmentally adhering a stretchable film to an inside surface of a stretchable nonwoven fabric is employed as a back sheet, is disadvantageous in that the stretchable nonwoven fabric is more expensive not only in the raw material thereof but also in the cost of the production process thereof, compared to conventional non-stretchable materials, thereby increasing the cost to general consumers.
Also, where the stretchable composite sheet is employed as a back sheet, this sheet is required to serve as a leakage-preventing sheet, and thus must be non-permeable to liquids. The liquid non-permeable sheet causes the wearer of the resultant diaper to feel stuffy due to the body heat of the wearer or when the ambient temperature increases. To prevent the stuffiness, a plurality of ventilating holes are formed in portions of the side flaps on the back sheet except for the crotch portions of the flaps. These ventilating holes cause the disadvantage that if the wearer of the diaper, who is lying down, especially sleeping, excretes, the excrement can leak through the holes and stains the garment of the wearer. Therefore, it is necessary to impart a leakage-preventing property to the entire surface of the back sheet of the diaper.
Further, the underpants type disposable diaper disclosed in the above-mentioned Japanese Unexamined PCT Publication No. 1-503473, Japanese Unexamined Patent Publication No. 4-161,152, Japanese Unexamined Patent Publication No. 5-76,565 and Japanese Unexamined Patent Publication No. 6-63,074, have an outermost layer consisting of a single ply of a nonwoven fabric, or a liquid-absorbent pad member partially adhered to the outermost layer sheet. Therefore, this diaper is disadvantageous in that the outermost layer sheet sometimes is broken or tears, or during wearing, the liquid absorbent pad member is sometimes removed from the outermost layer sheet so that the diaper is deformed.